1) Field of the Invention
The present invention relates to an apparatus capable of effectively performing an ion-exchange treatment of dispersions (hereinafter may called suspensions), more specifically to an apparatus capable of carrying out an ion-exchange treatment of dispersions and liquids generating dispersoids to ensure the collection of their corresponding deionized dispersion and dispersion media, and separating and collecting the dispersoids thereof as valuable acidic fine particles and/or basic fine particles.
2) Description of the Related Art
Since a fixed bed of a particulate ion-exchange resin, which has been filled in an ion-exchange column, traps suspensoids (suspended particles), it is difficult to subject any suspensions and liquids generating suspensoids to an ion-exchange treatment. It is an usual method to treat a suspension by ultrafiltration in advance to remove its suspensoids and then to ion-exchange the thus-treated suspension. However, the limited pH value of a suspension to be treated is required to permit its ultrafiltration. The pH must hence be adjusted by addition of an acidic or basic substance prior to the ultrafiltration. As a result, the concentration of electrolytic ions in the resultant filtrate is increased.
In FIG. 3, is illustrated a circuit of a conventional deionizing and purifying apparatus for water, which is intended to remove the suspensoids from a suspension, thereby obtaining a purified suspension medium such as deionized water. Before and after an ion-exchange treatment column A (anion-exchange resin column) and an ion-exchange treatment column C (cation-exchange resin column), there are provided for use various kinds of filters F including an ultrafilter in plural stages. Since their filters trap suspensoids without regard for their chemical properties (for example, acid or base), it is impossible to classify the suspensoids by their chemical properties to separate and recover them. Therefore, the suspensoids trapped are discarded together with filter media in general.
FIG. 4 illustrates a flow chart of a conventional effluent treatment by which suspensoids are collected and recovered from a suspension. A flocculant (electrolyte) is added to a suspension (effluent), suspensoids are flocculated and settled in a settling separator 42 to separate them, and a supernatant liquid was then recovered through an overflow tank 43. It is impossible to obtain purified suspension medium and suspensoids due to the addition of the flocculant. The suspensoids can also be not classified by their chemical properties.
In order to enhance the level of deionization, it is essential to use a mix bed system in which both anion-exchange and cation-exchange resins are mixed with each other or to preset a particular circulation circuit (Japanese Patent Publication No. 59793/1986). According to the conventional ion-exchange treatment, it is possible to prepare deionized and purified water. It is however impossible to usefully use suspensoids contained in a suspension.
It is disclosed in Japanese Patent Application Laid-Open No. 149805/1982 to subject various kinds of functional fine particles including pigments to an ion-exchange treatment in order to remove electrolytes remaining in the fine particles. Such a method has not come to be used in industry because there is no specific treatment means or apparatus which is industrially practicable.
In order to carry out an ion-exchange treatment of a suspension without any clogging, it has been proposed to cause the suspension to pass through an ion-exchange resin layer upward so as for the resin not to accumulate (Japanese Patent Application Laid-Open No. 92028/1984). In order to suspend and fluidize the ion-exchange resin in this method, however, a large space provided with a special device therein is required, a pump having a high lift for passage of the suspension must be selected, and excess energy is also required, in comparison with downward passage of the suspension, by which the ion-exchange resin is left at rest. In addition, such a method does not always prevent clogging in an ion-exchange treatment of a suspension liable to flocculate. It is therefore difficult to use such a method on an industrial scale.